The present invention relates to vehicle speed warning and regulation systems. It finds particular application in conjunction with selectively using sign recognition for warning a vehicle operator about a vehicle's speed and controlling a vehicle speed and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
Speed limits and driving conditions along any given route may change frequently, particularly in urban settings. In addition, along a given route speed limits may change according to the time of day, such as during school hours or rush hours. The current and accepted method of informing the driver of the speed limit is through posted speed limit signs on the side of the road. However, when multiple speed limit signs are posted for a single section of road (e.g., both a school time speed limit and a non-school time speed limit in a school zone), a driver must determine which speed is applicable.
Warning systems have been developed for notifying an operator of a vehicle when the speed of the vehicle is undesirable. Cruise control systems have been developed for regulating the speed of a vehicle. Some of these systems incorporate cameras for imaging passing speed limit signs, which post the current speed limit, as the vehicle travels. A processing unit associated with the warning and/or cruise control systems evaluate(s) images of the speed limit signs for identifying the posted speed limit. The processor then warns the operator and/or regulates the speed of the vehicle to achieve the posted speed limit.
As noted above, a single section of road in, for example, a school zone may include multiple speed limit signs or a single speed limit sign with different posted speed limits that are in effect at different times. Since exceeding a posted speed limit can have negative consequences such as personal injury, property damage, and fines from speeding tickets, current warning and cruise control systems elect the lower speed limit regardless of whether that lower limit is currently in effect.
A lower speed limit (e.g., 20 mph) in a school zone may only be in effect a few hours each school day. For non-urban highways, the non-school time posted speed limit may be significantly higher (e.g., 50 mph). Therefore, a camera based warning and/or cruise control system that determine(s) the current posted speed limit by evaluating images of speed limit signs may unnecessarily warn and/or slow a vehicle in the school zone during times when the school speed limit is not in effect.
The present invention provides a new and improved apparatus and method for warning and cruise control systems.